Solutions

ACROSS
1 Ashpit.
AS+H+PIT
5 Assembly.
(anag.)
9 Have it made.
(two meanings)
10 Send.
(two meanings)
11 Blue Nile.
BLUE NILE (line anag.)
12 Tartan.
TAR+TAN
13 Abide.
AB+IDE (die anag.)
15 Petersham.
(anag.)
18 Bridewell.
B+RID+E+WELL
19 Mandy.
M(AND)Y
21 Edison.
EDIS+ON (no side rev.)
23 Olive-oil.
(two meanings)
25 Into.
(hidden)
26 Lord's table.
(anag.)
27 Bear arms.
B+(EAR AR)MS (a rare anag.)
28 Nation.
NAT+I+ON


DOWN
2 Stall.
(two meanings)
3 Pretended.
PR+E+TENDED
4 Titbit.
T+I+T+B+I+T
5 A Farewell To Arms.
(anag.)
6 Sweetpea.
SWEET+PEA
7 Muser.
M+USE+R
8 Lend a hand.
LE+(ND A) HAND (DNA anag.)
14 Barn dance.
(anag.)
16 Spare part.
SPARE+PART
17 Swindler.
SWINDLE+R
20 Wilson.
(anag.)
22 Stour.
ST+OUR
24 Igloo.
IG+LO+O (GI rev.)